"She was a very loyal wife to a man who it was sometimes very hard to be loyal to.
"But I have to say Muldoon would never hear a word against Thea.
"In his eyes she was always right."
Mr Nelson said he remembers an occasion after Muldoon had retired from politics.
"It was at the unveiling of a statue to Sir Keith Holyoake in Wellington.
"Afterwards Thea grabbed me and we got talking on the street while Muldoon sat impatiently in his car a short distance away.
"Finally he yelled out to her "come on Thea, come on".
Mr Nelson said while he had fond memories of Dame Thea his favourite prime minister's wife to work for was Glen Rowling followed by Norma Holyoake.
Mrs Holyoake, he said, was a great talker.
"Any time you got talking to her you knew it would be at least half an hour before you could get away.
"I knew more about the lives of the VIP ladies in Wellington than just about anyone else."
Mr Nelson said he would not be taking the trip to Auckland to attend a funeral service for Dame Thea on Tuesday.